1. Field of the Invention
The present invention relates to an exhaust muffler for use in an automotive vehicle such as, for example, a motorcycle.
2. Description of Related Art
The exhaust muffler used in the currently commercially available automotive vehicle such as, for example, a motorcycle is known having an interior thereof divided by at least one partition wall member into a plurality of chambers, with exhaust gases flowing through those chambers. In particular, the Japanese Patent No. 3020909 discloses the exhaust muffler of a structure, in which those two partition wall members used to particular chambers are formed with first and second communicating passages, respectively, an outlet port of the first communicating passage being laid to confront an outlet port of the second communicating passage so that sound waves caused by exhaust gases flowing into those particular chambers can be bumped with each other within such particular chambers to thereby counteract the sound waves.
It has, however, been found that the exhaust muffler disclosed in the above mentioned patent fails to exhibit a sufficient exhaust silencing effect. In particular, at a high speed rotation at which the flow of the exhaust gases is high, the flow resistance is so high as to result in the reduction in engine output and, on the other hand, no sufficient silencing effect is available.